“But Jehu was acting deceptively in order to destroy the ministers of Baal.”
He destroyed Baal worship, which was a good thing. “Yet Jehu was not careful to keep the law of the Lord, the God of Israel with all his heart.”
He obeyed a “little bit”. Incomplete obedience is still disobedience.

How often do we do that? We only keep the commandments we like or read the Scriptures that say what we want to hear, or simply ignore parts of the Bible. Ouch!

Jehoiada, the priest, put the Levites in the proper places in the temple to protect the boy king Joash. “Joash was seven years old when he began to reign”. Can’t imagine our seven year old grandson leaving his Lego blocks long enough to rule a nation.

Once Joash was in place, Jehoiada placed the priests, the Levites in the temple to do what God had ordained them to do. Notice “Joash did what was right in the eyes of the Lord all the years Jehoiada, the priest instructed him”.
We need Godly spiritual advisers to counsel our leaders in the governments of both church and nation. 

The people then got rid of Baal worship. However, like Jehu in Israel, their obedience was only partial. They still continued to offer sacrifices in the high places. There was a remnant of pagan worship.

Not too different from many churches today that still cling to celebrations that are not God-ordained, in effect “burning incense” to pagan rituals. 

So what’s the application from today’s reading for us as individuals? It’s pretty simple. Is the church doing what God’s Word says or is the church doing what the world says?

Jer 5:31
The prophets prophesy lies, the priests rule by their own authority, and my people love it this way. But what will you do in the end?

Ultimately it comes down to the individual. What will we do in the end? Will we worship God in their way or in God’s way? (Deut 12:4 You must not worship the LORD your God in their way.)